Metal-clad switch gear



March V28, 1939. A. L FLETCHER ET AL METAL- CLAD SWTCH GEAR Filed Oct. 9, 1937 5 Sheets-Sheet l March 28, w39- A. L. FLETCHER ET A1. 2,153,755

METAL-CLAD SWITCH GEAR 3 Sheets-Sheet 2 Filed Oct. 9, 1937 March 2S, 1939.. A. Lv FLETCHER ET AL 3537756 METAL-CLAD SWITCH GEAR Filed Oct. 9, 1937 5 Sheets-Sheet 3 Ff; f2. D

2563 wrTNEssEs; KT

` Patented Mar. 28, 1939 UNITED STATES METAL- CLAD SWITCH GEAR Arthur L. Fletcher, Pittsburgh, and Benjamin I.

Hayford, Wilkinsburg, Pa., assignors to Westinghouse Electric & Manufacturing Company,

East Pittsburgh, Pa.,

Sylvania Application October 9,

12 Claims.

Our invention relates, generally, to switchgear apparatus, and, more particuiarly, to switchgear apparatus of the metal-clad type wherein all energized parts are normally enclosed within 5 metal housings or casings.

In the construction of metal-clad switchgear it is the usual practice to provide a compartment or super-structure above the main structure for housing the potential transformers, fuses and l current limiting resistors which are required for energizing the instruments and relays associated with the switchgear equipment. Access to the fuses for the potential transformers is usually provided through a door on the` front of the l transformer compartment which makes it possible to inspect and replace the fuses when necessary. However, in prior structures there is danger of the inspector coming in contact with the energized terminals of the fuse supports, which are on the high potential side of the transformers, since no provision is made for disconnecting the transformer from the power conductors while the inspection is being made.

An object of our invention, generally stated,

is to provide for so mounting a potential transformer in a switchgear structure that the transformer may be readily disconnected from a high potential power conductor.

A more specific object of our invention is to provide an enclosed compartment for housing a potential transformer and its associated apparatus wherein the apparatus in the compartment may be readily deenergized without deenergizing the power conductor to which it is normally connected.

Another object of our invention is to provide an enclosed compartment for housing a potential transformer and associated apparatus to which access cannot be had While the apparatus is energized.

A further object of our invention is to provide for so interlocking the door to a compartment for housing electrical apparatus that the door cannot be opened while the apparatus is connected to a power conductor and the apparatus cannot be connected to the conductor While the door is opened.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilledin the art.

In accordance with one embodiment of our invention potential transformers and their fuses and current limiting resistors are mounted on a drawout truck with disconnecting contacts for 'the primary and secondary circuits which permits withdrawing the transformers and fuses to a disconnected position before handling the fuses or associated equipment. An interlock mechanism is provided for the door to the transformer 6o compartment to prevent opening the door unless a corporation of Penn- 1937, Serial N0. 168,203 (Cl. -298) the truck is fully withdrawn to the disconnected position, thereby deenergizing the fuses and the transformers. When the door is open with the truck in the disconnected position, the interlock prevents moving the truck to the connected position without first closing the door.

For a fuller understanding of the nature and objects of our invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawings, in

which:

Figure 1 is a view, partially in side elevation and partially in section, of a potential transformer and its supporting structure embodying our invention;

Figs. 2, 3, and 4 are enlarged detailed views showing various positions of the interlocking mechanism utilized in the structure illustrated in Fig. 1; Figs. 5 and 6 are enlarged views showing the closed and the opened positions of the latch for the door of the transformer and fuse compartment;

Figs. 7 and 8 are enlarged views in plan and front elevation, respectively, of a portion of the truck and cell structure showing the door and the interlocking device in the closed position;

Fig. 9 is a View, similar to Fig. 7, showing the door in the opened position;

Fig. 10 is a view, similar to Fig. 8, showing the interlocking device in a disengaged position;

Fig. 11 is a view, partially in side elevation and partially in section, of a modification of the invention;

Fig. 12 is a view, in side elevation, of a portion of the structure shown in Fig. 11, with the potential transformer in the disconnected position; and,

Figs. 13, 14 and l5 are detailed views showing the latching device for the truck in various positions.

Referring now to the drawings, and particularly to Fig. 1, the structure shown comprises a sheet metal housing or cell II) having a bottom II, top I2, back wall I3 and side walls (not shown). The housing I0 is designed to rest upon the top I4 of a steel cubicle, such as is usually utilized to enclose heavy-duty circuit breakers and other switch-gear apparatus. y

As shown, an insulating sleeve I5, which may be composed of porcelain or other suitable material, is mounted horizontally near the bottom of the housing I0. The sleeve I5 is provided with a partition I6 in which is mounted a stationary contact memberl I 1, which is normally engaged by a contact member I8 of the flexible sleeve type .usually utilized for the main disconnect contacts on removable circuit breakers. The contact member I1 is connected to a conductor I9 which extends through the top wall I4 of the supporting cubicle and may be connected to one of the main power conductors or buses usually located near the top of the cubicle structure.

In accordance with the usual practice in high voltage installations, a potential transformer 2| is provided for reducing the voltage applied to the instruments and relays associated with the switching equipment. The usual current limiting resistor 22 and fuse 22 are provided for the protection of the potential transformer 2l. The fuse 23 is of the removable type and is mounted in fuse clips 24 disposed on supporting studs or terminals 25 on the transformer 2l. One termi-1 nal of the resistor 22 is connected to one end of a horizontally mounted terminal 26, the other end of which is disposed inside of the sleeve i5 and carries the contact member IB, thereby con necting the potential transformer 2| to the con-n ductor I8. The terminal 2B may be of the con denser bushing or any other type suitable for high tension service.

In order that the fuse clips 24 may be readily deenergized when it is necessary to remove the fuse 23 for inspection or replacement and also that the resistor 22 and the transformer 2l may be inspected without danger to the inspector, the transformer 2i, the resistor 22, the fuse 23 and the terminal 2E are all mounted in, a renioy able truck structure 21. 4The truck 21 is mount ed on. rollers 28 which run in channebshaped tracks 29 disposed on the sides of the housing i0, thereby permitting the entire truck assenti bly to be moved outwardly to a disconnected position in which the Contact member I8 is disengaged from the Contact member i1 to deenergize the transformer 2i and its associated apparatus.

When the truck 21 is in the disconnected posi tion, the secondary terminal oi the transformer 2l, which is connected through a conductor and a contact'member 32 on the truck 21 to stationary contact fingers 33 in the housing ill, is also disconnected, thereby completely isolatun ing the transformer 2i.

The outward movement oi." the truck 21 is nor-n mally limited by stop members 34 disposed on the side of the truck to engage an upwardly extending flange 35 on the bottom of the housing IU However, if it is desired to remove the transformer entirely from. the housing the truck. may be raised sufiiciently to permit the stops 3d to clear the flange Since most alternating current power systems are three phase, the track 21 is designed to conw tain three transformer units similar to the one shown. However, the truck may be constructed to contain any number of units. insulating riers 3B may oe provided between the terminals oi the different units, as shown.

In order that access may be had to the trans former compartment, a hinged door 31 is provided on the front of the truck 21. The door 31 is provided with handles 38 for withdrawing the truck from the operating position and for openlng the door.

With a view `towards affording maximum safety for the operator at all times, a mechanical interlocking mechanism 4l is provided. The inter locking mechanism is designed to prevent the door 31 from being opened unless the truck 21 is fully withdrawn to the disconnected position, thereby deenergizing the transformer 2l and its associated apparatus. The interlocking device also functions to prevent the truck 21 from being inserted to the operating position without the door being closed. In this manner, access to the transformer compartment can be gained only when the apparatus in the compartment is deenergized.

As shown more clearly in Figs. 2 to 4 and '1 to 10, inclusive, the interlocking mechanism 4I comprises an interlocking bar 42, which is pivotally mounted on one side of the truck 21; an operating plate 43, which is pivotally mounted on the inside of the door 31; a push button 44 for actuating the plate 43 to raise the interlocking bar 42; a hook member 45, which is secured to the inside of the door 31 and disposed to engage a laterally extending projection 46 on one side of the interlocking bar 42 when the truck is in the operating position, and a lug 41 so disposed on the side of the housing l0 that it is engaged by the interlocking bar 42 when the truck is in the operating position, as shown in Fig. 2, and also when the truck is withdrawn to the disconnected position, as shown in Fig. 4.

The interlocking har 42 is provided with a pin 43 which extends through a slot 48 in the side of the truck 21 and is engaged by the operating plate 43 to raise 'the interlocking bar 42 to the position shown in Fig. 3 when the push button 44 is depressed. in this manner the bar d2 may be raised to disengage the lng 41 and permit the truck to be Withdrawn from the heus ing by means of the handles 38.

However, it will be seen that it is impossible to open the door 3l while the truck 21 is in the operating position, since the projection 4E on the bar 42 would be engaged by the member 45 on the door 31 to prevent the door from being opened. Furthermore, the door is held closed by a latch 5i which is pivotally mounted on the opposite side of the truck from the interlocking mechanism to engage a hook member 52 secured to the door 31.

When the truck 2l is withdrawn to the disconnected position and the push button 44 released, the bar 42 drops to the position shown in Figs. 4 and 10 in which a shoulder 53 on the bar 42 engages the lug 41 on the housing lil. It will be seen that the end of the bar 42 is lowered sufficiently to permit the hook member 45 to pass over the projection 46, thereby permitting the door 31 to be opened. The door may now be opened by releasing the latch iii from the hooi: 52 which may be accomplished at this time by the operator reaching around the side oi" the door 3l to raise the which is now accessible from the side oi the truolr.1

As shown in Figs. Y?! to il), the end of the bar 42 is so bent at right angles that extends into a slot 54 provided in the flange of the door 31 when the door is swung to the open position, as shown in Fig. 9. In this manner the truck 21 is prevented from being inserted into the housing in while the door is open, since the bar 42 is prevented from being raised by the end of the bar striking the flange 55 on the door 31, thereby preventing the shoulder 53 from being disengaged from. the lug 41 on the side of the housing I0.

Furthermore, a member 56 is diagonally disposed across a portion of the flange 55 on the door 31 to be above the laterally extending end of the bar 42 so long as the door is only par tially closed, thereby preventing the interlocking mechanism from being released to permit the truckto be inserted into the housing, which makes it necessary for the door to be fully closed before the truck can be inserted to the operating position, in which the contact member I8 engages the contact member I1 to energize the transformer 2|.

In the modification of the invention shown in Figs. 11 to l5, in which corresponding parts are is hinged at the top of the truck structure. The

truck 21 is mounted on rollers 28 and may be withdrawn from the operating position to deenergize the transformer 2| and its associated apparatus in the manner hereinbefore described. The truck is retained in the operating position by a latch 62 which is pivotally mounted at one side of the housing on the track 29.

When it is desired to withdraw the truck from the housing to gain access to the fuses 23, the end of the latch 62, which projects through the front of the truck, may be lowered (as shown in Fig. 14) to cause the latch to disengage a lug 63 which is secured to the movable truck 21. The truck 21 may then be Withdrawn to the position shown in Fig. 12 in which the latch 62 engages a lug 64 similar to the lug 63 on the truck 21.

When the truck 21 is fully withdrawn to the.

disconnected position, as shownin Fig. 12, the edge of the door 6I will clear the front of the housing i0, thereby permittingthe door to be opened to gain access to the fuses 23 as well as the transformers 2l and the current limiting resistors 22.

When it is desired to insert the truck into the housing, the latch 62 may be disengaged from the lug 64 by pressing down on the handle of the latch, access to which may be had from the side of the housing. However, it is necessary that the door 6i be closed before the truck can be fully inserted into the housing, since, as shown in Fig. 2, the door si is so hinged at the top of the truck structure that it will prevent the truck from being fully inserted into the housing to the operating position, in which position the contact member it engages the contact member I1 to energize the transformer 2i. Therefore, it will be seen that in this structure access cannot be gained to the transformer compartment until the truck has been withdrawn to a position in which the transformer is deenergized and the truck cannot be restored to the operating position until after the door 5l has been closed to close the compartment.

From the foregoing description it is apparent that we have provided a simplied and economical structure which makes it possible to completely disconnect an instrument transformer and Aits associated apparatus from a high tension power conductor and which insures a. maximum degree of safety for the operator. While the structure herein described is designed for utilization in switchgear apparatus of the metal clad type, it will be understood that the present structure may be utilized readily in apparatus' of other types.

Since numerous changes may be made in the above described construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the forel going description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergized when the truck is'withdrawn from the housing a predetermined distance, a-door on the truck for permitting access to said apparatus when opened, means for preventing the opening of the door unless the truck is withdrawn from the housing said predetermined distance, and releasable means for normally limiting the outward movement of the truck.

2. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, means for preventing the opening of the door unless the truck is withdrawn from the housing said predetermined distance, and means for preventing the insertion of the truck into the housing to connect the apparatus to the power conductor without the door being closed.

3. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, means for preventing the opening of the door unless the truck is withdrawn from the housing said predetermined distance, means for preventing the insertion of the truck into the housing to connect the apparatus to the power conductor without the door being closed, and means on the truck cooperating with means on the housing for normally limiting the outward movement of the truck.

4. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted Iin said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting ac` cess to said apparatus when opened, means for preventing the opening of the door unless the truck is withdrawn from the housing said predetermined distance, means for preventing the insertion of the truck into the housing to connect the apparatus to the power conductor without the door being closed, and means on the truck cooperating with means on the housing for normally limiting the outward movement of the truck, said last named means being disposed to permit the truck to be removed entirely from the housing.

5. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, means for preventing the opening oi the door unless the truck is withdrawn from the housing said predetermined distance, means for preventing the insertion of the truck into the housing to connect the apparatus to the power conductor without the door being closed, and manually releasable means ior normally limiting the outward movement of the truck from the housing.

6. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, and means on the truck for preventing the opening of the door unless the truck is withdrawn from the housing said predetermined distance.

'7. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the hous ing, said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, and means on the housing for preventing the opening of the door unless the truck is withdrawn from the housing said predetermined distance.

8. In switchgear apparatus, in combination, a. housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, and means on the housing for preventing the opening of the door unless the truck is withdrawn from the housing said predetermined distance, said door being disposed to prevent the insertion of the truck into the housing to connect the apparatus to the power conductor without the door being closed.

9. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing,

said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, and an. interlocking bar on the truck cooperating with means on the door for preventing the opening oi the door unless the truck is withdrawn from the housing said predetermined distance.

10. In switchgear apparatus, in combination,

a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergized when the truck is withdrawn from the housing a predetermined distance, a door on the truck Afor permitting access to said apparatus when opened, and an inter" locking bar on the truck cooperating with means on the door for preventing the opening of the door unless the truck is withdrawn from the housing said predetermined distance, said intern locking bar being disposed to releasably latch said vtruck in the housing in the operating position and also in the disconnected position.

11. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said'housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenergiaed when the truck. is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, an interlocking bar on the truck cooperating with means on the door for preventing the opening of the door unless lthe truelt is withdrawn from the housing said predetermined distance, said interlocking bar being disposed to releasably latch said, truck in the housing in the operating position and also in the disconnected position, and manually operable means on the door lfor releasing said bar from the latched position.

12. In switchgear apparatus, in combination, a housing, a truck structure removably disposed in said housing, electrical apparatus mounted in said truck structure, a power conductor disposed in the housing, means carried by the truck for connecting said apparatus to the power conductor when the truck is fully inserted in the housing, said apparatus being deenei'gized when the truck is withdrawn from the housing a predetermined distance, a door on the truck for permitting access to said apparatus when opened, an interlocking bar on the truck cooperating with means on the door for preventing the opening of the door unless the truck is withdrawn :from the housing said predetermined distance, said interlocking bar being disposed to releasably latch said truck in the housing in the operating position and also in the disconnected position, manually operable means on the door for releasing said bar from the latched position, and means on the door for preventing the unlatching of said bar to insert the truck into the housing while the door is open.

ARTHUR L. FLETCHER. BENJAMIN I. HAYFORD. 

